Three secondary schoolboys smoking an illicit cigarette in Hyde Park, London. (Photo by Evening Standard/Getty Images). May 1972

Models Felicia Verna and Crystal Boyd wearing Stacey Angela during the Fallen Hearts Fashion Experience at Symphony Space on May 31, 2011 in New York City. (Photo by Jemal Countess/Getty Images)

A lesser or red panda stands on its hind legs at Chiba Zoological Park on May 20, 2005 in Chiba, Japan. The panda can maintain the position for over 10-20 seconds at a time. (Photo by Koichi Kamoshida/Getty Images)

A villager pours brine into troughs at ancient salt fields on May 5, 2005 in Yantian Village on Hainan Island, China. (Photo by China Photos/Getty Images)

Dogs and owners run during of 4k pet run “A Race with a Cause”, organized to raise funds for a shelter for rescued dogs in Caracas, Venezuela, Sunday, April 30, 202. (Photo by Ariana Cubillos/AP Photo)

Opera singers perform in the pool “AquAria PALAOA” during a rehearsal at the swimming pool Neukoelln on April 27, 2011 in Berlin, Germany. The premiere of the underwater opera AquAria PALAOA is on May 1st. (Photo by Andreas Rentz/Getty Images)

Members of the South Korean Special Weapons and Tactics team exhibit their skill during anti-terrorism exercises at a training camp on May 30, 2005 in Seoul, South Korea. (Photo by Chung Sung Jun/Getty Images)

The Facebook website is displayed on a laptop computer on May 9, 2011 in San Anselmo, California. An investigation by The Pew Research Center found that Facebook has become a player in the news industry as the popular social media site is driving an increasing amount of traffic to news web sites. (Photo Illustration by Justin Sullivan/Getty Images)